How to use a Ballistics Program

[gleason.chapman]

1. You need your bullet weight, your Muzzle Velocity, your Ballistics Coefficient and your sight in yardage.

2. Google is your friend for most of this. Lets sayyour trying to find the Ballistic Coefficient of a TC SW. So enter"TC Shockwave Ballistic Coefficient" intoGoogle and look for 300g SW and something from Hornady. You will see in looking thru the Google search, that the BC is .250. If you Google Hornady SST 300g you will find it at .250 here:

http://www.hornady.com/images/2008_sell_sheets/SST-ML.pdf

3. Go to:

http://www.sav10ml.com

Then Click "Enter"

Then on left hand side scroll to NEW Bullet Drop Calculator (this will open a new window)
and click on it.

Put your Bullet weight, MV, BC, sight-in yards and output increments into the interface.

[gleason.chapman]

4. Your output will be this.

This for for a MV of 1900 FPS, 300g bullet and a .250 BC.



5. Now do yourself a favor and in IE mark the site as a Favorite and print this to PDF,
instructions on how to print to PDF are here:

http://tinyurl.com/2rwg99

Knowing your limits in hunting is very very important (you must practice at your furthest distance). Most ML hunting rifles can be zeroed for 3" high at 100 yards and this makes them effectively 175 guns, shooting thru a 6" pipe from zero to 175. You can get to 200 yards by upping your charge (150g of 777 for example).

Best Wishes on Bullet Selection and Knowing your drop and therefore your guns limits and your shooting ability.
Chap

[gleason.chapman]

6. Now lets use the Program to do a little "scientific inference". What will be my bullet drop between and 0 to 150, with a 150 yard zero if I increase my MV by 100?

Here it the chart for 1700 FPS, with .250 BC of TC SW, 300g bullet, 150 yard Zero.

[gleason.chapman]

Here is 1800 fps, same everything else:

[gleason.chapman]

Here is 1900 fps, same everything else:

[gleason.chapman]

2000 fps, rest stays same:

[gleason.chapman]

Now the last 2100 fps, since most inline ML reach about this as their Max velocity:

[gleason.chapman]

Lets intrepret this output, the high point of the arc for a 150 yard zero is 75 yards, so lets pick that, since we don't want to shoot for the neck and miss it all together. Here are the figures at 75 yards:

Fps inches
1700 + 3.6
1800 + 3.1
1900 + 2.7
2000 + 2.4
2100 + 2.1

So we gain a full 1/2" in better trajectory going 100 fps more from 1700 to 1800 fps. We gain a whole 1.2" by taking speed up from 1700 to 2000 and 1.5" by taking the speed up 400 fps from 1700 fps.Most rifles have a sweet point for accuracy, but can go up 100 fps to gain some trajectory improvement. You also know then over most of the range your shooting that when you shoot say 1800 fps your shooting thru a 6" pipe from 0 to 175 yards with a 150 yard zero. You can do the same thing with 250 vs 300g bullets and see where that gets you or compare and flat nose bullet vs a spire pointed bullet like the SST. Other may want to chime in here on how they use their ballistic program.
Chap Gleason

[oldsmellhound]

I flunked math in high school

[gleason.chapman]

ORIGINAL: oldsmellhound

I flunked math in high school

OSH,
"Speak softly and carry a big stick - you will go far." It is good you don't need to know a lot of math to shoot MLers well, but carring a big smokepole will get you far .
Chap